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CN-121020582-B - High-performance asphalt-based porous carbon and preparation method and application thereof

CN121020582BCN 121020582 BCN121020582 BCN 121020582BCN-121020582-B

Abstract

The invention discloses a high-performance asphalt-based porous carbon and a preparation method and application thereof, wherein the preparation method comprises the following steps of heating and stirring refined asphalt, introducing oxygen-containing gas, and carrying out sectional heating oxidation treatment to obtain oxygen-containing modified pre-oxidized refined asphalt; the preparation method comprises the steps of heating pre-oxidized asphalt to different temperatures in stages in an inert atmosphere to perform pre-carbonization, placing a pre-carbonized product in a hydrogen-containing mixed atmosphere, dynamically regulating and controlling a carbonization process according to asphalt components, mixing the carbonized product with potassium hydroxide and sodium hydroxide mixed alkali, performing step activation in a multi-temperature zone, and washing and drying to obtain the asphalt-based porous carbon. According to the invention, the refined asphalt is directly used as a carbon source raw material, a part of oxygen-containing hard carbon structure is obtained through pre-oxidation, a carbonized precursor with little volatile component is obtained through low-temperature pre-carbonization, the porous carbon is subjected to moderate graphitization by carbonization, the conductivity of the skeleton is improved, and the skeleton is further subjected to pore-forming by activation, so that the porous carbon material with high performance is obtained.

Inventors

  • ZHENG JUNHUA

Assignees

  • 炭衍科技服务(无锡)有限公司

Dates

Publication Date
20260508
Application Date
20250825

Claims (5)

  1. 1. A preparation method of high-performance pitch-based porous carbon for a silicon-carbon negative electrode is characterized by comprising the following steps of: (1) Pre-oxidizing refined asphalt, namely heating and stirring the refined asphalt, introducing oxygen-containing gas, and carrying out sectional heating oxidation treatment to obtain oxygen-containing modified pre-oxidized refined asphalt; the sectional temperature-rising oxidation treatment comprises the following steps: (11) Heating and stirring for 1-4 hours at the softening point of +20 ℃; (12) Introducing air with the flow rate of 600-2000 mL/min or O 2 /N 2 mixed gas with the O 2 volume content of 5%, fully contacting the gas with the liquid asphalt by ventilation bubbling, heating to 220-280 ℃ at the heating rate of 2-10 ℃/min, and keeping the temperature for 0.1-4h; (13) Finally, raising the temperature to 270-330 ℃ at the temperature raising rate of 3-12 ℃ per minute, and keeping the temperature for 0.5-5h; the oxygen content of the obtained pre-oxidized refined asphalt is 2-8at%, and the softening point is 100-280 ℃; (2) Low-temperature step pre-carbonization, namely, pre-carbonizing the pre-oxidized asphalt obtained in the step (1) by heating to different temperatures in stages in an inert atmosphere; The low temperature step pre-carbonization comprises: (21) In the atmosphere with the flow rate of N 2 and the flow rate of 150-200mL/min, the purity of which is more than 99.99 percent, the temperature is raised to 300 ℃ at the heating rate of 1-5 ℃/min, and the temperature is kept for 30-120min; (22) Then continuously heating to 400 ℃ at a heating rate of 2-6 ℃ per minute in the atmosphere with the flow rate of 150-200mL/min of N 2 with the purity of more than 99.99 percent, and preserving heat for 50-140min; (23) Finally, in the atmosphere with the flow rate of 150-200mL/min of N 2 and the purity of which is more than 99.99 percent, the temperature is raised to 500 ℃ at the heating rate of 2-6 ℃/min, and the temperature is kept for 50-140min; (3) Medium-temperature carbonization, namely placing the pre-carbonized product obtained in the step (2) in a hydrogen-containing mixed atmosphere, and dynamically regulating and controlling the carbonization process according to asphalt components; the hydrogen-containing mixed atmosphere is H 2 /N 2 mixed gas with the volume ratio of H 2 to 10 percent and the flow rate is 150 to 200mL/min; The carbonization temperature is 600-650 ℃, the time is 60-240min, the heat is preserved for 120-150min when the beta resin content is 22-25%, and the heat is preserved for 90-120min when the beta resin content is more than 25%; (4) Mixing the carbonized product obtained in the step (3) with potassium hydroxide and sodium hydroxide mixed alkali, performing step activation in a multi-temperature zone, and then washing and drying to obtain asphalt-based porous carbon; the mixed alkali is a mixture of KOH and NaOH according to the mass ratio of 1:1, and the mass ratio of the material alkali is 1:1.0-2.5; The step activation comprises heating to 700 deg.C at 2-6 deg.C/min in N 2 atmosphere with inert purity of >99.99% and flow rate of 200-800 mL/min for 30-60min, heating to 750 deg.C at 2-6 deg.C/min for 60-90min, and heating to 900 deg.C at 2-6 deg.C/min for 60-120min.
  2. 2. The process according to claim 1, wherein in step (1), the refined asphalt satisfies the conditions of QI content of 80-8000ppm, ash content of 100-600ppm, carbon content of 90.00wt% or more, sulfur content of 1000ppm or less, volatile content of 30-60wt%, coking value of 45.00-85.00%, softening point of 100-230 ℃ and beta resin content of >22%.
  3. 3. The method according to claim 1, wherein in the step (4), the washing step is carried out by washing 3 times with acid and water respectively after natural cooling.
  4. 4. A high-performance pitch-based porous carbon for a silicon-carbon anode, which is prepared by the method according to any one of claims 1 to 3, wherein the pitch-based porous carbon has a BET specific surface area of 1586 to 2103m2/g, a pore volume of 0.67 to 0.94cm3/g, an average pore diameter of 1.34 to 2.82nm, a microporosity of 75.3 to 96.4% and a mesoporosity of 2.1 to 24.3%.
  5. 5. Use of the pitch-based porous carbon according to claim 4 in a silicon-carbon negative electrode, characterized in that: The gram capacity of the silicon-carbon anode is 1477-2076mAh/g, and the initial effect is 86.6-94.7%; The capacity retention rate of 0.1C circulation for 200 times is 81.3-92.3%, and the rate retention rate of 6C/1C multiplying power is 80.6-88.7%.

Description

High-performance asphalt-based porous carbon and preparation method and application thereof Technical Field The invention belongs to the technical field of porous carbon materials, and particularly relates to high-performance pitch-based porous carbon, and a preparation method and application thereof. Background The CVD silicon carbon is formed by firstly depositing nano silicon on a porous carbon skeleton, then cracking carbon-containing gas such as acetylene to form amorphous carbon, and depositing the amorphous carbon on the surface of the nano silicon to form a porous carbon-nano silicon-amorphous carbon structure, wherein the nano silicon provides active material capacity, the porous carbon provides active sites, a conductive skeleton and an expansion space, and the amorphous carbon provides a coating layer and a conductive agent. The current process for preparing porous carbon is to pretreat a carbon source to obtain a precursor, and then treat the precursor according to the pretreatment-carbonization-activation-washing-drying procedures. The quality of the carbon source, carbonization and activation process flow are core links of porous carbon preparation, the development degree and connectivity of the size of pores are directly determined, the electrochemical performance of a subsequent silicon-carbon anode of the porous carbon is further directly determined, meanwhile, the cost of the porous carbon is also determined, such as patent CN202510367469.7, the carbonization heating rate, the heat preservation duration, the atmosphere flow rate and the temperature are also determined, the pore size, the structural stability, the state of a pore surface group and the connectivity of a multi-stage pore are directly influenced, such as patent CN118221099B, the cost of the asphalt-based porous carbon is lower, the initial efficiency and the circulation performance are lower, such as patent CN202411929086.6, but the existing common finished asphalt on the market is not a carbon source designed for the porous carbon, and the obtained asphalt-based porous carbon material cannot be customized for the porous carbon in the carbon source and the process, and cannot meet the initial efficiency and the circulation performance requirements of lithium-electricity silicon carbon. The porous carbon obtained by the above method has the following problems: The carbon source performance is poor, the composition of the carbon source is not carefully selected, so that the porosity development degree, the conductivity and the mechanical performance of the carbon material cannot be considered, the cost of using the mesophase pitch as the carbon source is too high, or the conventional pitch component is unsuitable, even if the coking value reaches the standard, the mechanical performance cannot meet the requirement of expansion cycle for more than 2000 times, or the aromaticity is insufficient, the subsequent conductivity is poor, the internal resistance is high, and the multiplying power and the heat generation are serious. Poor carbonization effect, namely collapse of micropores and mesopore pores caused by burst in volatilization diversity of asphalt-based carbon sources due to improper temperature and temperature rise, and obtaining the porous carbon material with the main macropores, or residual organic matters in the pores to prevent subsequent silicon atom deposition. The activation effect is poor, most of the prior asphalt-based carbon sources adopt alkali activation with the alkali dosage being more than 3 times for obtaining developed microporous structures, but the effective utilization rate of the alkali is low, so that the porous carbon has higher cost, high environmental-protection waste water pressure, high equipment corrosion maintenance cost and high sewage treatment cost. Disclosure of Invention The invention aims to provide high-performance pitch-based porous carbon, a preparation method and application thereof, wherein refined pitch is directly adopted as a carbon source raw material, and a high-performance porous carbon material is obtained after pre-oxidation, low-temperature pre-carbonization, medium-temperature carbonization and medium-high-temperature activation, a part of oxygen-containing hard carbon structure is obtained after pre-oxidation, a carbonized precursor with extremely low volatile content is obtained after low-temperature pre-carbonization, the porous carbon is moderately graphitized by carbonization, the conductivity of a skeleton is improved, and the skeleton is further porous by activation, so that the high-performance porous carbon material is obtained. In order to achieve the above purpose, the invention adopts the following technical scheme: in a first aspect, the present invention provides a method for preparing a high performance pitch-based porous carbon. A preparation method of high-performance pitch-based porous carbon comprises the following steps: (1) Pre-oxidizing refined aspha